Carbohydrates are an essential component of life as a structural and energy storage component, and as stabilization, recognition, signaling and communication agents. Increasing interest in glycobiology has been precipitated by recent findings that cell surface carbohydrates are critically involved in cell adhesion and, thus, in cell-cell interaction. The advent of molecular biology in this field has enabled scientists to manipulate carbohydrate expression and study glycoprotein function.
Difficulties in the Study of Sugar Structures
Part of the variability seen in saccharide structures is due to the fact that monosaccharide units may be coupled to each other in many different ways, as opposed to the amino acids of proteins or the nucleotides in DNA, which are always coupled together in a standard fashion. The study of saccharide structures is also complicated by the lack of a direct template for their biosynthesis, contrary to the case with proteins where their amino acid sequence is determined by their corresponding gene.
Saccharides are also secondary gene products and as such are generated by the coordinated action of many enzymes in the subcellular compartments of a cell. Thus, the structure of a saccharide may depend on the expression, activity and accessibility of the different biosynthetic enzymes. This means it is not possible to use recombinant DNA technology in order to produce large quantities of saccharides for structural and functional studies as has been used extensively for protein studies.